In general, a portable radio telephone set comprises a dial operation unit having a plurality of push buttons for generating a calling signal and a telephone number signal of a called party. In this portable radio telephone set, a calling party presses the selected push buttons in turn to generate a telephone number signal which is supplied to a control unit of the telephone set, so that the telephone set of the calling party is connected through a communication channel to a telephone set of the called party.
A portable radio telephone set having a voice recognition apparatus has also been proposed. In this portable radio telephone set, a calling party voices a telephone number of a called party by facing the telephone set, so that the voice recognition apparatus recognizes the voice of the calling party and generates a telephone number signal of the called party. Consequently, the telephone set of the calling party is connected through a communication channel to a telephone set of the called party.
However, the former portable radio telephone set has a disadvantage in that a limitation occurs in the amount the size of the telephone set can be reduced, because the plural push buttons must be provided on a main body of the telephone set to generate a telephone number signal.
In addition, the latter portable radio telephone set has a disadvantage in that it is difficult to dial a telephone number of the called party in a confidential manner, because the telephone number is voiced at a predetermined voice level by the calling party.